A hopper wagon is a type of freight railway vehicle for transporting bulk commodities. The bulk commodities are stored in a hopper wagon body. The hopper wagon body is supported by an underframe. Bogies may be coupled to the underside of the underframe to allow the hopper wagon to move along a railway.
The bulk commodities are loaded into the hopper wagon body through an inlet and discharged through an outlet. The inlet is an aperture that is conventionally formed in the top of the hopper wagon body whilst the outlet is an aperture that is conventionally formed in the bottom of the hopper wagon body. In covered hopper wagons, the inlet is provided with a covering system to protect the bulk commodities stored in the hopper wagon body.
In certain covered hopper wagons, the covering system may comprise a simple removable sheet. However, this type of covering system requires manual operation and the sheet must be stored when it is not in use. Other known covered hopper wagons have covering systems with one or more closable doors that open and close under a sliding or rotating action. Advantageously, the doors of these types of covering system remain attached to the hopper wagon body and may be driven to slide or rotate using automatic or semi-automatic drive means. However, covering systems with a slidable door require sufficient space to locate the door as it slides along a longitudinal axis of the hopper wagon to reveal the inlet aperture. Hence, the size of the inlet and/or spacing between adjacent hopper wagons is compromised. Covering systems with a clamshell door that pivots in an arcuate path around the hopper wagon body are difficult to control and are at risk of failing by opening unexpectedly under gravity. Covering systems with a door that rotates in a substantially vertical plane between an open position and closed position are conventionally designed such that the door is rotatably mounted by a hinge that is arranged internally, within the hopper wagon body. As a result, bulk commodities loaded in the hopper wagon body may interfere with the hinge and door, become compacted and ultimately inhibit the operation of the covering system. Moreover, due to the internal mounting arrangement of the hinge and door, rainfall may run off the door towards the hinge and into the hopper wagon body. Also, air flow apertures formed in the door may compromise the water tightness of the covering system.
Embodiments of the present invention seek to provide an alternative and improved covering system for a hopper wagon inlet. Embodiments of the present invention seek to address and ameliorate the problems associated with conventional covering systems.